Biodegradable microparticles may be used to deliver physiologically active substances such as, small molecule drugs, hormones, proteins, diagnostics, and other medically active agents to a patient. Microparticles are suspended in an aqueous diluent to make a suspension, which can be injected parenterally through a needle. They may also be implanted as a solid. After injection, the microparticles degrade and gradually release agents to the body. Biodegradable microparticles may reduce the frequency of injections, as the physiologically active substance is released gradually into the body. The microparticle size distribution affects the required gauge and other characteristics of the needle. More flowable microparticles may be easier to fill into vials and may be more easily injected with a large gauge (smaller diameter) needle. Once in the body, the rate of release and the concentration of the physiologically active substance may be related to the microparticle size, the microparticle size distribution, the initial concentration of the physiologically active substance, and other characteristics of the microparticles. Such biodegradable microparticles also need to meet health and safety regulations for contaminant concentrations including the solvents used to prepare the microparticles. Thus, a need for microparticles with superior syringability, injectability, flowability, uniformity, and purity characteristics exists. Forming microparticles involves forming an emulsion from an oil component and an aqueous component. The process for forming an emulsion can affect the characteristics of the microparticles, and the efficiency of the emulsion forming process may impact the availability and acceptability of microparticles with physiologically active substances. Further, there is a need for a process for the production of microparticles that requires less space than conventional processes. The methods and systems described herein provide solutions to these and other needs.